There are two different JVMs provided by OpenJDK-derived JVMs: the
client JVM and the server JVM. These JVMs use different compilers for
producing executable machine code from Java bytecode. The client JVM is
tuned for startup time and memory footprint while the server JVM is
tuned for maximizing performance. The difference in performance between
the two VMs can be substantial. The client JVM check ensures that
Elasticsearch is not running inside the client JVM. To pass the client
JVM check, you must start Elasticsearch with the server VM. On modern
systems and operating systems, the server VM is the
default. Additionally, Elasticsearch is configured by default to force
the server VM.